On Tuesday, Standard & Poor's cut Greek bonds to “junk” status. Yesterday it cut the credit rating of Spain, which has a much larger economy. Portuguese debt was downgraded as well. With Europe a major market for American exports, recent uncertainty has led to some doomsday scenarios. Is Europe's banking system in trouble? Is the Euro losing its value? What will Europe's financial problems mean for the US? Newsweek and Washington Post columnist Robert Samuelson is author of The Great Inflation and Its Aftermath: The Past and Future of American Affluence.